The present invention generally pertains to lighting for use on a vehicle, and more specifically, to exterior lighting provided by light emitting diodes (LEDs) or other solid-state light sources that are mounted on a flexible substrate, for use on the rear and/or the front of a vehicle.
Exterior lighting for automobiles and other types of motorized and non-motorized vehicles typically includes one or more incandescent lamps that include a tungsten filament. This filament is turned white hot by an electrical current that flows through it. Because such lamps produce considerable heat, they typically burn out after only a few hundred hours of use, and are much less efficient than other types of light sources. On vehicle tail light and head light assemblies, a curved reflective surface is usually included behind the bulb to ensure that sufficient light intensity is directed in a desired direction. The reflective surfaces for incandescent tail lights, brake lights, and backup lights used on the rear of vehicles often require several inches of depth. As a result, the lighting assemblies at each side on the rear of a vehicle must intrude into the vehicle trunk by the required depth of the assembly and its reflective mounting for the incandescent lamps that are used therein. The volume required for the lighting assemblies within the trunk is substantial and is unavailable for storing objects placed into the trunk.
Each model of vehicle typically requires a different rear light assembly to accommodate the specific shape of the exterior surface in which the rear light assemblies are mounted. The colored plastic lenses used for these assemblies are relatively expensive, easily broken in even low-speed collisions with objects, and expensive to replace. Because each make and model of vehicle typically uses a different rear light assembly lens, it is expensive to maintain a stock of these parts and after a few years, they become unavailable from a dealer and can often only be obtained from wrecking yards.
Many of the same problems arise in connection with head lights, running lights, parking lights, and turn signals used on the front and sides of vehicles. The orientation of conventional head lights must be adjusted so that the light they emit primarily illuminates the lane of traffic in which the vehicle is traveling, is directed downwardly at the road surface, and does not blind drivers of oncoming vehicles in an adjacent lane. Improperly adjusted head lights contribute to accidents caused by poor illumination of the road surface and/or glare that distracts a driver of an oncoming vehicle.
Accordingly, it would be preferable to provide a non-incandescent light source that does not use a conventional bulb for exterior vehicle lighting. Such a light source should ideally be sufficiently flexible to conform to a curved exterior shape of a vehicle, and minimize the need to provide a different assembly for each different model and make of vehicle. Also, these light sources should not require any significant depth, but instead should be mountable on the exterior surface of a vehicle, requiring almost no internal volume in the trunk, engine compartment, or sidewalls of the vehicle. Light sources should have an expected lifetime of many thousands of hours, e.g., for the life of the vehicle. If damaged, these light sources should be replaceable at relatively low cost. Furthermore, any capability required for focusing or directing the light emitted by the sources in a desired direction should be included with the light sources and should require little additional depth.
In accord with the present invention, a flexible vehicular lighting assembly is defined. The lighting assembly is adapted to mount on and conform to an external surface of a vehicle. Depending upon the configuration of the lighting assembly, it can provide illumination of a surface over which the vehicle is traveling, indicate an intention of a driver to turn the vehicle in a specific direction, stop the vehicle, and/or provide an indication of a location of the vehicle. The lighting assembly includes a flexible substrate having a rear surface and a front surface. A plurality of flexible conductive traces are disposed on the flexible substrate and are adapted to connect to an electrical system of a vehicle to receive an electrical current. In addition, a plurality of solid-state light emitting devices are mounted in a spaced-apart array on the flexible substrate and are electrically connected to the plurality of flexible conductive traces so that these sources can be energized by the electrical current, causing the them to emit light. A transparent flexible envelope extends over the plurality of solid-state light emitting devices, providing protection against abrasion, but enabling the light emitted by the plurality of solid-state light emitting devices to pass through the transparent flexible envelope. The rear surface of the flexible substrate is adapted to seat against and conform to an exterior surface of a vehicle.
Furthermore, in one embodiment, the flexible vehicular light assembly preferably includes a plurality of reflective surfaces, each disposed around a different one of the plurality of solid-state light emitting devices. These reflective surfaces focus the light emitted by the plurality of solid-state light emitting devices in a desired direction, away from the front surface of the flexible substrate.
In one embodiment, an adhesive is applied to the rear surface of the flexible substrate for use in adhesively attaching the flexible substrate to an exterior surface of a vehicle. If desired, the flexible substrate can be attached to the vehicle in a shallow recess formed on the outer surface of the vehicle.
Depending upon the desired application, the plurality of solid-state light emitting devices are preferably arrayed in a plurality of groups, and those in each group emit light of a different color than the devices in the other groups. For example, the solid-state light emitting devices in a first group may emit white light, the devices in a second group may emit red light, and those in a third group may emit amber light. This type of vehicular light assembly is preferably adapted to mount on a rear portion of a vehicle, adjacent to one side, to selectively emit the amber light and when periodically energized (blinking), indicating a direction in which the vehicle will turn, the red light being emitted for indicating that the vehicle is slowing, and the white light to illuminate a ground surface over which the vehicle is backing.
In another configuration, the plurality of light emitting devices emit white light, and the flexible vehicular light assembly is adapted to be mounted on a front exterior surface of a vehicle, to illuminate a surface over which the vehicle may advance.
Another preferred form of the flexible vehicular light assembly further includes a totally internally reflective (TIR) lens for each of the plurality of solid-state light emitting devices. The TIR lenses focus the light emitted by the plurality of solid-state light emitting devices away from the front surface, in a desired direction. Yet another embodiment includes a TIR lens that covers a plurality of the solid-state light emitting devices and focuses the light that they emit in a desired direction.